1. Field of the Invention
The present invention relates to a Light Emitting Diode (LED) package. More particularly, the present invention relates to the LED package including photo diode which detects actual quantity of output light to stabilize light output.
2. Description of the Related Art
Recently a Light Emitting Diode (LED) has been used as a next-generation lighting source due to its higher-power and higher efficiency compared with other light sources. In general, unlike light source for a simple indicator, lighting source is required to maintain stability of light output. However, the LED has disadvantages in that temperature change resulting from its own heat generation alters light output and peak wavelength.
Therefore, there is a need for a package combining the LED used as light source with a photo diode capable of maintaining light output and peak wavelength uniformly by conducting real time feedback control of the LED.
Conventionally, photo diodes have been simply mounted on a lead frame on which LEDs are provided, in positions adjacent to the LEDs. U.S. Pat. No. 4,794,431 discloses a side-by-side arrangement in which a pair of photo diodes are arranged on two sides adjacent to the LED, as shown in FIG. 1.
According to the reference cited, by arranging the pair of photo diodes on two adjacent sides of the LED on the lead frame, respectively, the photo diodes can be arranged more adjacent geometrically, to absorb side light of the LED effectively, and thus the light output of the LED can be precisely monitored.
But such an arrangement according to the reference cited inevitably causes physical separation since an LED package and a photo diode package are arranged separately on the lead frame. This renders it unlikely that optical connection efficiency is heightened. In addition, since a great deal of noise may interfere with the detected light due to change in other external environments, it is hard to expect high reliability.